1. Field
Embodiments relate generally to fabrication of semiconductor devices, and more particularly to a method of fabricating a gate dielectric using a replacement gate flow process.
2. Background
Replacement gate processes may be used for fabricating transistors with a wide selection of gate materials. In a replacement gate flow process, an entire transistor may be fabricated with a sacrificial gate electrode and a sacrificial gate dielectric. After all of the high temperature fabrication processes have taken place, the sacrificial gate electrode and the sacrificial gate dielectric are removed to form a gate opening and a desired gate material is deposited in the gate opening.
One problem associated with the conventional replacement gate flow process is that the corner regions of the gate trenches can have non-ideal gate dielectric due to deposition conditions or conformity issues. In conventional subtractive gate processing, a reoxidation process is typically performed on the gate stack in order to grow a small amount of oxide layer at the edges of the gate dielectric layer near the corners to improve the reliability and leakage of the device. However, in replacement gate processes, the conventional reoxidation processes cannot be utilized because the gate side walls are already sealed off before the reoxidation process can be performed.